The real advantages of being a mage are portability, the teleport and portal spells, and the ability to conjure food and water. Granted food is very inexpensive, it's just nice that you don't have to worry about stocking up before you go anywhere because you can whip up a batch whenever you want. Other than that it is a fully functional damage dealer.
Mage is no more gear dependent than any other class. In fact, we are probably less gear dependent while leveling because of all our snares and movement speed reducing effects. You can spam frost bolt on a mob all day long and it will never catch you, whereas a warrior has to fight straight up and is dead if he can't put out enough damage to kill his foe(s) before his health gets to 0.
As far as leveling goes, it's an easy class to level with some impressive burst damage and good crowd control for sticky situations.